SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d5d812e8806984b90afe88c97db981e84a9ce3ace78916d56a528440ff52db0' 
  AND token = 'gsWPwQzFSrOODVSlbGGPiUmUqQomKF17nqYOub1pD0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}